The subject matter disclosed herein relates generally to sensors that may be used to provide position/orientation information for an instrument, implant or device used in a medical context, such as in a surgical or interventional context. In particular, the subject matter relates to calibrating a sensor assembly to improve the accuracy and precision of the position/orientation information.
In various medical contexts it may be desirable to acquire position and/or orientation information for a medical instrument, implant, or device that is navigated or positioned (externally or internally) relative to a patient. For example, in surgical and/or interventional contexts, it may be useful to acquire position and/or orientation information for a medical device, or portion of a medical device, even when the device or relevant portion is otherwise out of view, such as within a patient's body. Likewise, in certain procedures where an imaging technique is used to observe all or part of the position and orientation information, it may be useful to have position and orientation information derived from the tracked device itself that can be related to other data, such as image data that may be contemporaneously acquired. In such medical contexts, electromagnetic (EM) sensors may be implemented to provide the position/orientation information for the medical instrument, implant, or device.
It may be desirable to calibrate the EM sensors before use in a surgical or interventional context, so that position/orientation information may be obtained with a high level of precision and accuracy. Unfortunately, for medical applications that last several minutes to a few hours, an initial calibration of the EM sensor may not sufficiently reduce position/orientation errors originating at the EM sensor over the entire course of the procedure. Accordingly, it may be desirable to calibrate EM sensors as they are operating in surgical or interventional applications so that a high level of precision and accuracy can be maintained while position/orientation information is obtained for the medical device. While it may be desirable to calibrate EM sensors at the location of use, in practice it may be difficult to provide for portable calibration methods that do not need large calibration equipment. Furthermore, it may be difficult to provide fast, high-throughput calibration for EM sensors as they are being used to acquire position/orientation information during surgical or interventional procedures, such as, for example, when the EM sensors are used within a patient's body.